In an interchangeable lens camera, a body and a lens are provided with respective apertures, whose coupling allows the lens to be mounted on the body. The apertures of the body and the lens may be respectively called a body-side mount and a lens-side mount. The body-side mount and the lens-side mount each may have an aperture diameter and a flange back distance unique to itself. Basically, a body-side mount of a body may take a lens having a lens-side mount adapted for the body-side mount.
Meanwhile, when it is desired to couple, to the body, a lens that includes a lens-side mount different from the lens-side mount adapted for the body-side mount of the body, the lens may be mounted on the body with an adapter interposed therebetween. The adapter may perform not only conversion of coupling shapes between the body-side mount and the lens-side mount having different aperture diameters, but also conversion of groups of contacts provided for communication between the lens and the body. Accordingly, the adapter may include, for example, a first group of contacts on a rear surface, and a second group of contacts on a front surface. The first group of contacts may make contact with a group of contacts of the body. The second group of contacts may make contact with a group of contacts of the lens. Wirings may be inserted through inside the adapter, in order to electrically couple the first group of contacts to the second group of contacts (for example, refer to Patent Literature 1).